Means for counting electrical impulses



June 27, 1950 D. s. RIDLER MEANS FOR COUNTING ELECTRICAL IMPULSES Filed Oct 22. 1946 TR'IO TR/OO 0/ T-H REG TR/OOO REG IOO Patented June 27, 195% MEANS FOR COUNTING ELECTRICAL E/IPULSES Desmond Sydney Ridler, London, England, assignor to International Standard Electric Corporation, New York, N. Y.

Application October 22, 1946, Serial No. 704,839 In Great Britain September 14, 1945 Section 1, Public Law 690, August 8, 1946 Patent expires September 14, 1965 The main feature of the invention consists in counting by means of thermistors.

According to another feature of the invention an electrical impulse counting train comprises thermistors, the circuits of which are so arranged that the thermistors become conductive in turn in response to successive impulses.

Thermistors have been in use for some years and are characterized by a temperature coefiicient of resistance which may be either positive or negative and which is moreover many times the corresponding coefficient for a pure metal such as copper. This property renders thermistors. particularly suitable for a variety of special applications in electric circuits.

Various different materials are available for the resistance element of a thermistor, these various materials having difierent properties in other respects; as one example, a resistance material having a high negative temperature coefficient of resistance comprises a mixture of manganese oxide and nickel oxide, with or without the addition of certain other metallic oxides, the mixture being suitably heat treated.

Thermistors have been employed in two different forms: (a) known as a Directly Heated Thermistor and comprising a resistance element of the thermally sensitive resistance material provided with suitable lead-out conductors or terminals, and (1)) known as an Indirectly Heated Thermistor comprising the element (a) provided in addition with a heating coil electrically insulated from the element. A directly heated thermistor is primarily intended to be controlled by the current which flows through it and which varies the temperature and also the resistance accordingly. Such a thermistor will also be effected by the temperature of its surroundings and may therefore be used for thermostatic control and like purposes with or without direct heating by the current flowing through it. An indirectly heated thermistor is chiefly designed to be heated by a controlling current which flows through the heating coil and which will usually, but not necessarily, be different from the current which flows through the resistance element, but this type of thermistor may also be subjected to either or both of the types of control applicable to a directly heated thermistor.

More detailed information on the properties of thermistors will be found in an article by G. L

'7 Claims. (01. 235-92) 2 Pearson in the Bell Laboratories Record Dec. 1940, page 106.

The invention will be clearly understood from the following description of one embodiment shown in the accompanying drawing showing a counting circuit comprising three trains TRIU, TRHW, TRlllllO of indirectly-heated thermistors, twenty in each, arranged to count groups of ten impulses each. There are carry-over arrangements between the trains to allow them to count respectively up to ten, up to one hundred, and up to one thousand. Registers are provided arranged to be operated from the counting trains.

It will be seen that apart from T20 of each train the heater coil of which also has a special circuit controlled solely by starter contacts RS4, RS5, and RS6, the circuits for the heater coils H and resistance elements R of the odd and even thermistors of each train, Tl, T3 TH, and T2, T l T20, respectively are similar. In each train the resistance element of TI is in series with the heater coil of T2 the resistance element of T2 is in series with the heater coil of T3, and so on. The resistance element of T20 is in series with the heater of TI, and the heater of T29 also has an individual heater circuit as described above. The heater coil circuits of the even-numbered thermistors other than T20 are connected to the front contacts of impulse repeating contacts AI, B2, C2 respectively, and the heater coil circuits of the odd numbered thermistors are connected to the back contacts of said repeating contacts.

When the circuit is taken into use, a key Kl is operated to energise a relay RS which disconnects the current source at RSI, RS2 and RS3 from impulsing contacts Al, Bl, Cl and connects current sources at RS4, RS5 and RS6 to the heater coils of the last thermistors T20 of each train.

On release of Kl, relay RS releases and the closure of contacts RSI, RS2, RS3 completes circuits through Al, Bl, Cl back the heated thermistors T20 and the heater coils of the thermistors TI. Thermistors Tl heat up and thermistors T26 remain conducting in this circuit.

The circuits closed through the resistance elements of even thermistors T2, T4 in series with the heater coils of T3, T5 Tlll will be without effect as the resistance elements have high resistance.

Operation of a second key K2 now completes an impulsing circuit for relay A including impulse springs IS which can be operated in any suitable known manner to operate relay A. Contact Al opens its back contact and closes its front contact completing a circuit through the heated resistance element of Ti of TRlil and the heater coil of T2, which heats up.

At the end of the impulse, relay A releases and contact Al returns to its back contact, cornpleting a circuit through the heater coil of T3 and the heated resistance element of T2 so that the heater coil of T3 heats up. While contact Al is off its front contact, the thermistor T2 cools so that when battery is again connected to the front contact of Al current will not flow through T2 and the heater coil of T3.

The beginning and end of the second impulse heats up thermistors T4, T5, the third impulse heats up thermistors T6, T1, the fourth impulse heats up thermistors T8, T9, and so on. As impulsing progresses, the thermistors in turn cool down and cease to be conducting, so that at any time there is only one thermistor of the train conducting, and a preceding one cooling down.

The tenth closure of front contacts AI will therefore operate relay B through the resistance element of thermistor i 9, and the heater element of thermistor 20. When relay A again releases, relay B is released and a circuit is completed through the resistance element of T20 and the heater element of TI.

The energisation of relay B operates contacts Bl to heat upthermistor T2 of TR-lflll, and its release completes a circuit for heating thermistor T3 of this train. TRIOO remains in this condition while further impulses to relay A operate TRIS.

Each operation of relay B in response to ten impulses causes a further impulse to TRIBE). When TRIM! has received ten impulses from relay B, relay C will operate causing an impulse via CI to TRI 800 which operates in the same way as TR l and TRIM.

When TR-lllflll has received ten impulses relay D operates momentarily.

Registers REG), I00, I000 of any suitable conventional type are operated via contacts B2, C2 and Di, for each ten, one hundred, and one thousand impulses received. These registers record up to ten, and will therefore indicate the impulses counted to the nearest ten.

TRHJ, above, or TRIM], or any required combination of counting trains each containing any desired even number of thermistors could be used.

Such counting trains are applicable to many industrial applications.

What is claimed is:

1. An electric impulse counting circuit comprising one or more trains of thermistors connected in succession, means for energizing said thermistors in turn in response to a succession of impulses to be counted, and register means for indicating the number of impulses counted upon the type comprising a resistance element and a heating element, the resistance element of each thermistor being connected to the heating element of the succeeding thermistor.

3. A circuit in accordance with claim 2 further comprizing relay means connected in series with said preselected thermistor in each of said trains whereby receipt of a predetermined number of impulses energizes said relay thereby connecting a succeeding train of thermistors to count impulses of different orders, the counting train or trains for counting lowers orders being arranged to cause one impulse to be transmitted to the counting train of the next higher order each time each train has counted a predetermined number of impulses.

4. An electric impulse counting circuit comprizing one or more trains of thermistors, each thermistor of a train being connected in succession comprizing odd and even groups respectively connected in parallel, means for energizing said groups alternately in response to successive impulses received whereby successive thermistors are rendered conducting in turn, relay means connected to a predetermined thermistor in the succession said relay means being energized when said predetermined thermistor operates, and register means operated by said relay indieating an impulse count for each operation of said relay.

5. A circuit in accordance with claim 4 wherein said energizing means further comprizes impulse repeating relay means having contacts whereby said odd and even groups of thermistors are alternately connected in response to the operation of said contacts.

6. A circuit in accordance with claim 4 further comprising starting relay means including a key and having a plurality of contacts associated with each train whereby said counting circuit is ini tially placed in an operative condition.

7. A circuit in accordance with claim 1, in which each thermistor cools down when the succeeding thermistor circuit is completed.

DESMOND SYDNEY RIDLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,398,771 Compton Apr. 23, 1946 2,402,372 Compton et al June 18, 1946 2,405,096 Mumma July 30, 1946 

